Process for the separation and purification of argon and other rare gases of the atmosphere



Oct. 21. 1924. 1,512,268

E A. BARBET PROCESS FOR THE SEPARATION ANIJ PURIFICATION OF ARGON AND OTHER RARE GASES OF THE ATMOSPHERE Filed July 8 1919 3 Sheets-Sheet 1 Fig.1.

Oct. 21. 1924. 1,512,268

E. A. BARBET- PROCESS FOR THE SEPARATION AND PURIFICATION O; KCTON AND OTHER RARE GASES OF THE ATMOSPHEJ Filed July 8, 1919 3 Sheets-Sheet 2 Fig.2.

Zhuenfb I E. Eambef Oct. 21. 1924. v 1,512,268

E. A. BARBET PROCESS FOR THE SEPARATION AND PURIFICATION OF ARGON AND OTHER RARE GASES OF THE ATMOSPHERE Filed July 8, 1919 A 3 Sheets-Sheet 5 Fig. 3.

IIuZeh/or 5.4.Farbe) wiw Ahy.

. Patents ct. 21, 124,

have. invented certain new Processes for the Separation below the entrance of the air to If a proportion of the, volume of rectified air then with a properly con- EMILE AUGUSTIN BABBET, 0F PARIS, FRANCE.

GASES 0F Application filed 1 July 8,

Be it known that BET, a citizen of ing at No. 5 Rue provements in and Purlfication Gases of the Atmosphere,

lowing is a speci The present invention I, EMILE AUGUSTIN BAR- the French Republic, residde lEchelle, Paris, France,

and useful Imof Argon and Other Rare of which the folhas for its object to provide a process of producing in a pure state the rare gases contained in the air.

The present invention may be appliedto the various known apparatus liquid am In any case necessary to improve for rectifying it will be absolutely their working and more particularly to assure the absolute invariability of their rate ofworking by the use of the automatic or non-automatic means i of regulation.

1. Rectification 0 f of argon is inter trogen and that of oxygen.

of the column w ume to 4% of be withdrawn,

argon.-The volatility mediate between that of ni- Argon has therefore a tendency to accumulate in a stage hich is located a few plates be rectified.

rare gases equal in volstructed and properly worked plate column there should remain no argon at all either in the nitrogen at the gen at the tail, and ed 4% will conta n the 0.94% of argon contained in the air.

head, nor in the oxyconsequently the extract- The percentage of argon in this extraction will therefore be:

ever it be ng possible cause an increasingly of the argon will eontammate both the nito attain 100%, beconsiderable portion trogen at the top and the oxygen at the bottom.

The continuous rectification of any kind P of mixtures will be the more successful the more absolutely ing of the. said r and inthe first fluid to be recti regular is the rate of workectification, as above stated, lace it is desirable that the ed which is supplied to the I give pure argon at of the order-of succession N AND PURIFICATION OF ARGON AND OTHER RARE THE ATMOSPHERE.

1919. Serial No. 309,298.

. apparatus, should have as constant a comthis to be as a permanent feature.

The advantage will be great because it enables the purificat'on of argon to e performed in asingle column as subsequently described in detail, whilst if the'nitrogen is present in any considerable proportion, or instances. to 5%, and especially if the proportion is st ll greater, it will be necessary to employ two SUCCQSSlVQ. columns, one of which Wlll serve for instance for eliminating the oxygen, so that't'he second column will then only have to deal with a binary mixture 'of nitrogen and argon. In this last column the argon will be collected at the bottom of the apparatus and the nitrogen at the top thereof.

If desired the order of success on of these two operations may be reversed, that is to say, the first stage may be the elimination of the nitrogen as head products. 'Then from the bottom would be obtained a binary mlxture of gen and argon which would be treated in the second rectifying column in order to e-argonized oxygen at the tail;

Each of the two apparatus, irrespectively employed, will require its usual'accessories, such as condensers, coolers, recuperators, regulators, thermometers, etc. All these of course will have a capacity of one twentieth of those required for the main rectifier of the liquid air, but the complication will not be any the less inconvenient. Consequently it is of extreme importance to utilize the imthe result of requiring only a single argon column and of furnishing th s argon .in a state of absolute purity.

Instead of these'two continuous apparatus combined together, it would appear posof this first apparatus there. oxyin which they are rovements hereinafter described which have the head and completely I 'i ".a verysmall quantitly .sible to have recourse sim ly to the old fash- .ioned boiler rectifier wor g on successiye charges, and aproducing the fractio'nationsin the-time or er of the successive drawingsofi at the test cock. This arran ement however would be inapplicable for; ealing with liquefied gases. Such gases require the provision of reservoirs for storing the successive charges and likewise for storing the mixed products issuing from the test cock, which products require a fresh rectification.

The final yield of pure argon would be very small; The continuity of the rectifying oration isalone capable of solving t e pro lem completely and practically, but it is necessary to simplify the operation.

Apparatus for carrying the invention into efi'ect is illustrated in the accompanying ex mlple, in which Q igure 1 illustrates apparatus for recovering argon in a state of purity;

Flgure 2 illustrates apparatus for recovering pure neon and helium; and

Figure 3 illustrates an arrangement of I apparatus for recovering krypton and Xenon. I

- As above stated, a single continuous column for rectifyin the argon mi ht be sufficient provided t at there is on y a small proportion of nitrogen in the rawargoniferous liquid to be rectified. This first result is to be obtained from the liquid air rectifier.

' With-this object, some twenty plates are a 1 in the lower rtion A of the ,column A where the Sistillation proper of the liquid air takes place for the purpose of l efiectiitg a progressive exhaustion of the which passes'out at A2 while the oxygen passes out at Ow. The extraction of the ar "niierous liquid will take place only towargthe'middle of this plate column A. It is veryfieasy to regulate the workingof this apparatus in such a mannerthat at that of nitro'-.

stage t 'ere'will remain scarcely 1 gen in the argoniferous liquid. 1

ult may likewise be facilitated by the oooling'efl'ect due to employment of the cooler U which is a heat interchan r. ofany sui ble construction within which liquid air circulates. Since the 1 Ar from the air niferous liquid extracted at rectifier A A contains onl I of nitrogen, its rectific'qtion inthe singe column 2-3 will be] efi'ected by means of the rinciple of pasteurization or 'selfuri cation by automatic re-ebullition of t e refluxes.

impure argoniferous liquid extracted "at' Ar, j -hy .a= suitable cock, asses tlate itheicolumn' through a siphom' 'di fst l iion of. {chat is; as :ymt su r j of. 2, the

amazes liquefied, and gives up its latent heat of liquefaction to the liquid oxygen which is brought to ebullition.

A suitable proportion of this oxygen in the form of vapour is extracted at 11, and passes into recuperators on'its way to the gas-holder. These appliances are not shown.

The liquefied nitrogen in the worm '13 passes from the tra .13" and unites with The nitrogen becomes that contained in' t e worm 14 in A A,

which passes through the trap 14 and both bodies of nitrogen rise together through the 15 to the upper plate of the rectifier 1 The oxygen vapours that rise and bubble I up in the p ates 3are condensed and in their turn vaporize the argon and the nitrogen which is more volatile. than oxygen.

The plates. 2 efiect the rectification proper, the ob ect ofwhich is to retain the oxy n vapours that have been carried over, an to allow solely the argon and the nitrogen to pass over,

On'. leaving the upper plates of 2, the mixture which is very rich in ar on, nitrogen, passes to the con enser 4 whose tubes are immersed in pasteurized liquid nitrogen drawn from the to of the rectifier A' A. The proportion 0 this mixture is regulated by that in 4-there are liquefiedS or 9 tenths of the vapour argon+nitrogen which enters therein. This condensation is not capable of suitably fractionating' themixture'. In fact, the non-condensed portion will contain 'a, largerz proportion of nitrogen than the mixture passing into 4, but nevertheless there will be'a certain proportion oat nitroen still contaminatingthe liquefied argon. The 1i uid ,pnd non-condensed vapour pass into t e se arator 6. The gas composed of nitrogen an argon issues through 7 ,and returns at 9. into the rectifier A A ,"whereasthe liquefied portion returns through the siphon-tube 8 to the top of the plates 2 and constitutes the retrogradation owing- .to

the cock 5 in such a manner" but poor in which the refining or therectification will be effected .in the plates 2.

he reflux returned through 8 is subjected to ebullition on the upper'plates parts,- namely the When t more volatile nitrogen, are driven off-,and consequently on 3:151 pltitesflower downthe liquid is 09135 .on y o are argon name y pasteunz argon, which igextractedthrodgh the cock 10 and is conveyed to the coldunitsreculperator,

def not and thence toa meter and a e m i 98 to 99% quite free fromoxygen.

The liquid nitrogen employed for effecting condensation in 4; may be taken from any other source of supply, and particularly from the nitrogen taken from any source which servesto cool the heat interchanger U or from the nitrogen which is condensed in the worms of the base of the column. VVhatever its origin, the condensation produced by it has as its counterpart the production of an equivalent quantity of nitrogen vapour. This nitrogen vapour might be passed through recuperators of cold units and passed finally into the nitrogen gas-holder. It is however more simple to return it through the pipe 12 to the top of the rectifier A A to become mixed with the remainder of the pure gaseous nitrogen.

The argon rectifying column, which in the I drawings is shown closely combined with the continuous rectifierfor liquid air, might constitute a separate apparatus with recuperators, regulators, thermometers, liquid nitrogen. gas meters, etc., and more particularly in the case where a plurality of liquid air rectifiers should be comprised in one and the same works. in which case a single rectifying column might be allotted to deal with the total of the impure argoniferous liquids extracted in the various air rectifiers.

, 2. Rectification of neon and hZium.-The three more volatile gases existing in air, namely neon, hydrogen and helium may be extracted by subjecting the liquid nitrogen to expansion in a suitable device.

The expansion produces a slight evaporation and the latter carries over with it the three light gases which exist in air in only very minute quantities.

If the extractionnerformed in this manner corresponds to 2% of the volume of air brought into rectification. which 2% contains all the neon, hydrogen and helium it will be immediatel understood that the rear gases are 50 times more concentrated in this extraction than they were in the air.

The whole of the remainder consists of nitrogen. and the proportion of this nitrogen is stillso high that if this fnixture is subj ected to a suitable compression followed by an adiabatic expansion whilst doing work, a

. total liquefaction will be produced including the helium. The same result is obtained if the compressed gas is forced into a worm immersed in a bath of liquid nitrogen.

This mean that this mixture of nitrogen and light gases can give rise to a fresh continuous rectification analogous in its principle to the continuous rectification of liquid air, but suitably adapted for separating in a pure state the several components. This apparatus is shown in Fig. 2.

The mixture of nitrogen, neon, hydrogen and helium entering at N passes into a recuperator A, and thence passes to the compressor B which need only produce a pressure of 2 to 3 kgs. The hot compressed *gas is cooled in the water worm C, and passes hence to the recuperator A, andthence through the pipe D to the worm E immersed in pure liquid nitrogen.

The pure nitrogen is brought to ebullition and passes out at As; from which it may be passed through suitable recuperators, and

.thenceinto a gas meter, and finally into the gas-holder. Oi; it-may be conveyed simply and directly to the upper plates of the apparatus for rectifying liquid air.

The nitrogen mixed with rare gases is liquefied in the worm exactly at the rate that the pure nitrogen is vaporized. The resulting liquid rises in F. This constitutes the feed for the rectifying column H H. H

contains the distilling plates designed to cause the neon, hydrogen and helium to be given off from the liquid nitrogen. The liquid arriving at-the baseG, contains only pure nitrogen which will accumulate therein and overflow by way of the pipe Gf, indi-' cated in dotted line. into the base of the column in which the coil E is arranged. The plates H are rectifying plates; they are charged with liquid neon mixed with more or less nitrogen. A mixture of vapours of neon, hydrogen, and of helium issues from the top of the apparatus at K, but no nitrogen at all, although nitrogen preldominated so considerably in the feed at There is now to he described the manner in which there is produced at the base of H' the ebullition which is capable of effecting the rectifying distillation. The ternary mixture passing through a recuperator L and issucked by a powerful compressor M. The vapours under pressure are cooledby a water worm O and pass into the recuperator L. Thence they'pass to the worm situated in the base G containing pure nitrogen.

cient pressure to cause the whole of the neon and a portion of the hydro en to become liquefied in the worm in There is no objection to a small quantity of helium being carried over into' the liquefaction, whereas itwill be a great disadvantage? if the whole of the, neon were not condensed.

out of K passes The compressor 'M' will produce a sufl'i- The mixture of liquid and non-condense gas passes into the separator P.

The discharge of the gases is regulated by means of the cock p in such a manner as to leave the gases in P to have a pressure of about kg, this pressure being necessary in order that the liquid in P should rise of itself to the upper plate of H through the pipe P As above stated, this liquid is composed of neon and a certain proportion of hydrogen with traces of helium. The partial expansion occurring inP generates a small vaporization, wherebymore particularly helium and hydrogen are freed. On entering the top of H and being subjected to ebullition, the liquid loses the hydrogen which is much more'volatile than the neon, so that 12 or 3 plates lower down there can be extracted at Q the liquid pasteurized neon which is very pure and very thoroughly rectified. The re-vaporized hydrogen mixed with neon, recommences the cycle through the recuperator L, the compressor and the wormin G.

' The gases given oil at p consist only of hydrogen and helium if the compression in M has been sufiicient. This mixture passes through the usual cold units recuperators before passing into a gas meter and then into a special gas-holder.

' From this binary mixture pure helium may be obtained by introducing suflicient oxygen into the mixture to combine with the hydrogen causing the hydrogen and oxygen to combine and separating the Water thus formed from the helium which may then be stored in a gas-holder. Alternatively the absorbent properties of wood charcoal may be utilized in efi'ecting the separation of the hydrogen and helium.

- It is to be noted that there is a strict relation between the vaporization in the base G and the quantity of vapour contained at the top of the plates H. [Nevertheless owing to the loss of cold units by radiation it will be necessary to supply to the apparatus a quantity to make up for this loss. This quantity is added in the form of pure liquefied nitrogen which is intro-- duced into the apparatus by the inlet F 3. Rectification of the menon and lam pt0n.If the proportion of the two rare gases xenon and krypton obtained at the bottom of a liquid air .rectifier is reduced to a hundredthpart of the volume of the air subjected to rectification, and the whole of the krypton present in the ori 'nal volume of air is contained in this fractlon, it is obvious that the xenon and the krypton will be in a state ofjQO times. greater concentration than in the air. The remainder of the mixture consists of oxygen. Theanixture of xenon and tenlgmight The separated from by eudi omet- I through the siphon-tube 16 ric method, by adding hydrogen in a proportion to be determined, by analysis in order to combine with mixture. I

It would however be referable to make a fresh rectification, whic is not ditficult because the boiling points of the three gases are very far apart, namely:

Oxygen, degrees absolute, 55 krypton,

ifl'erence, 305; xenon, 164, ence, 43. Although the mixture is separation can be done in a single column owing to these great differences in temperature. A "The ternary mixture of oxygen, krypton,

a ternary; one, the

any oxygen in the xenon, is extracted in the liquid state from the large liquid air rectifier, and it is introduced continuously through X into the column R, R B (Fig. 3).

Y is a tubular apparatus with blind tubes, that is to say, tubes closed at their'u'pper ends and immersed in the ternary liq uid to berectified. This tubular apparatus represents the alcohol heater of ordinary distillin columns. The krypton vapours produce in R of 121 absolute bring this liquid to boiling, and drive almost the whole of the oxygen out of it. The boiling point of the mixture is very near 118 to 119 absolute, that is to-say, 27 to 28 higher than the boiling point of oxygen. The removal of the oxygen is therefore almost com lete.

The overflow of this liquid will ass own t t 'ddl of the column R R, 0 m1 0 B are the distilling lates, namely, the

plates for removing t e -kryptonr The thermometer T should indicate 164 absolute. A continuous extraction of this pure xenon is made at Xe for the urpose of delivering it into the gas-holder y way Gal pure xenon should remain in the boiler Sincea little oxygen may remain, pasteuri 'zation is performed, that is to say, a certain quantity of krypton vapours contaminated with oxygen is drawn at Kr and delivered by the pipe 17 into the base of R, whilst one .or two (plates lower down the re-boiled, pasteurize krypton wholly freed from oxygen is extracted at Kr. This liquid will pass as before through recuperators and a gas'meter before entering its gas-holder. R are the oxygen rectifying plates designed for freeing the oxygen from the carried-over krypton. For this purposes. rete. rogradation -1s required. This retrogradetion is efl'ected in the tubular apparatus Z composed of blind tubes immersed liqi uid nitrogen. -This liquid nitrogen Iwi come from a liquid air rectifier; it will onter at 18; will be converted into vapour that will issue at A2 and enter the top of the rectifier A, A. The liquefied oxygen will redescend on the plates forcing out the krypton. The gaseous oxygen is extracted at. 00c and is passed through recuperators and a gas meter into the gas-holder, or it may be admitted into the bottom of the large air rectifier.

There still remains to describe the manner in which the whole of this column R, R, R is supplied with the necessar heat. For this purpose a worm is arrange in the base W, and through this worm there may be passed a current of dry air of normal temperature or of a temperature slightly below normal. This air will be cooled to about 173 0., absolute (100) C. and will be utilized for its cold unitsfor feeding the large liquid air rectifier.

What I claim is:

1. Process of obtaining the rare gases present in air, which comprises subjecting the liquefied mixtures of the rare gases containing a proportion of the commoner constituents of air to a continuous rectificationprocess, employing the condensed distillate of the higher boiling fractions derived in the rectification operation as a reflux and withdrawing a proportion of the reflux in the form of one of the rare constituents of air in a state of purity and as a liquid after it has been subjected to re-ebullition by the ascending gases.

2. Process of obtaining the rare gases present in air which comprises causing a liquefied mixture of the rare gases containing a proportion of .the commoner constituentsl'of air to travel in a downward direction and form a plurality of bodies of liquid, causing the gases produced by supplying heat to the mixture to travel in the reverse direction and pass through successive bodies of liquid, supplying to one of said bodies of liquid the condensed distillate of the higher boiling constituents of the mixture treated and withdrawing a neighbouring lower body of liquid which has been subjected to reebullition by the ascendlng gasesand is one of the rare constituents of air ina state of purity.

In testimony whereof I have signed my.

name to this specification.

- EMILE AUGUSTIN BARBET. 

